This invention relates to a coated endless belt of a woven material. More specifically, this invention relates to a continuous single-ply endless belt of woven material having a uniform thickness in a peripheral direction and coated with a non-stick material.
Conventional endless belts are used in packaging machinery and equipment, for food processing and other applications. Generally, the conventional endless belts are single-ply endless belts or two-ply endless belts. Conventional endless belts, sometimes referred to as release belts, can be used, for example as a conveyor belt. At a first temperature, an object is positioned on an outer surface of the endless belt. At a second temperature which is different from the first temperature, such as when the object is heated or melted, the physical properties of the object change and the object sticks or adheres to the outer surface of the endless belt and then when cooled the object being conveyed no longer sticks or adheres to the outer surface of the endless belt and thus releases from the endless belt.
A conventional single-ply endless belt 10, as shown in FIG. 1, has a first end portion 12 which overlaps and is secured, such as heat sealed or mechanically connected, to a second end portion 14. Single-ply endless belt 10 can fail or break at or near heat sealed portion 15, for example as a result of flexing or twisting single-ply endless belt 10 during use. Further, because of the non-uniform thickness at or near a heat sealed portion 15, single-ply endless belt 10 encounters considerable heat transfer problems which are not easily remedied.
As shown in FIG. 2, two strips of woven material, having approximately equal lengths, are connected to form a two-ply strip of woven material. A first end portion 21 of the two-ply strip is heat sealed to a second end portion 22 of the two-ply strip at a flex point or flex area 23 to form a two-ply endless belt 20. Two-ply endless belt 20 can fail at flex area 23 when two-ply endless belt 20 is flexed or twisted during use. Further, non-uniform heat transfer occurs at or near flex area 23.
There is an apparent need for a single-ply endless belt coated with a non-stick material and having a uniform thickness in a running or peripheral direction, to provide uniform heat transfer properties and increased strength.
It is an object of this invention to provide an endless belt made of a woven material and coated with a non-stick material, having a uniform thickness in a peripheral direction, which provides uniform heat transfer properties and increased tensile strength.
The above and other objects of this invention are accomplished with an endless belt made of a woven material coated with a non-stick material. Preferably, the endless belt is a continuous single-ply endless belt having a uniform thickness in a running or peripheral direction and preferably but not necessarily in a longitudinal or axial direction. Thus, the endless belt of this invention is better than conventional single-ply endless belts and two-ply endless belts, particularly for use in high temperature environments.
At a first temperature, an object is positioned on an outer surface of the endless belt. At a second temperature, different from the first temperature, the physical properties of the object change and the object sticks or adheres to the outer surface of the endless belt and then when cooled the object being conveyed no longer sticks or adheres to the outer surface of the endless belt.
In one preferred embodiment of this invention, the woven material of the endless belt is made of a plurality of warp fibers, oriented in a peripheral direction, and a plurality of weft or fill fibers oriented in a longitudinal direction. Preferably, each of the warp fibers and the fill fibers are made of a fiberglass material, an aramid material, a lightweight fire-resistant nylon fiber material and/or any other suitable high-temperature fiber.
In one preferred embodiment of this invention, the endless belt is coated with a non-stick material. Preferably but not necessarily, the non-stick material is a TEFLON material or polytetrafluoroethylene (PTFE) material.
During a coating process, a coating or a layer of a non-stick material is applied to the woven material so that the non-stick material coats at least a portion of the fibers forming the woven material. In one preferred embodiment of this invention, the portion of the fibers coated by the non-stick material includes fibers positioned near an outer periphery of the woven material. During one preferred coating process, the applied coating is heated to a fusion point or a sintering point, so that the non-stick material is fused or sintered to the fibers of the woven material and mechanically attached by solidifying or hardening within spaces of each fiber and spaces between adjacent fibers.